Her mother Kris Jenner is said to have known for longer but Khloe still kept her husband's secret for 'many months.'

The source added: 'Khloe was a real trooper. She's been living a nightmare.'

Khloe is alleged to have only told her family about Lamar's reported drug issues, after reports that he had an affair with Jennifer
Richardson for a year until March 2013 and a six-week fling with lawyer
Polina Polonsky at the start of the summer.

Meanwhile, some reports on Tuesday suggested Lamar has now returned home after being spotted driving into the gated community where he and Khloe share a home together.

The star is said to have 'looked gaunt' following a week where he was reported to have 'gone missing' for 72 hours - something later denied by his representative.

A source said previously: 'Lamar has lost a ton of weight in the last few months which triggered a lot of the concern amongst the family.

'Lamar does not want to go to rehab because pre-season training camps are just around the corner. 'He just doesn't care about anyone or anything right now. He has had it with the Kardashians and just wants to be left alone. Everyone is very, very, worried about him.'

Khloe has been married to Lamar for four
years, took to Twitter at the weekend to vent her fury after reports
emerged that claimed her spouse has been battling an addiction to
'hardcore recreational drugs,' including OxyContin, also known as
'Hillbilly Heroin'.

A free agent: Lamar was seen outside his Los Angeles mansion last week watching an assistant load bags into the boot of a car

She wrote: 'Really hard to sit here and listen to people talk s**t about my family! F**k you and shame on you! I'm too protective for this s**t!'

The 29-year-old TV personality is
also said to have taken 'no steps to file for divorce because she
believes there's still a chance for Lamar to be saved,' the report adds.

'They
really do love each other,' a source told People. 'But she really feels
that this problem is out of control, and she's hurt that he won't get
help.'

Despite the reports, no evidence has emerged of drug use and neither Lamar or Khloe have commented on it.

Meanwhile, Khloe's mother Kris Jenner arrived at her Los Angeles office in high spirits on Tuesday, looking unruffled by the reports.

Good spirits: Kris Jenner emerged in a leopard-print dress smiling broadly in the Woodland Hills area of Los Angeles